The CBS veteran, she has Attkisson, who has been with CBS News for two decades, had grown frustrated with what she saw as the network’s liberal bias, an outsize influence by the network’s corporate partners and a lack of dedication to investigative reporting, several sources said. She increasingly felt that her work was no longer supported and that it was a struggle to get her reporting on air.

At the same time, Attkisson’s reporting on the Obama administration, which some staffers characterized as agenda-driven, had led network executives to doubt the impartiality of her reporting. She is currently at work on a book — tentatively titled “Stonewalled: One Reporter’s Fight for Truth in Obama’s Washington” — that addresses the challenges of reporting critically on the administration.